Generally, an expandable vertebral body replacement device requires screws or other fasteners to achieve proper extension during vertebral body replacement. Additionally, certain vertebral body replacements may require screws or other fasteners to secure into position one or more components relative to one another. For example, certain expandable vertebral body replacements may have an outer cylinder that can be rotated about an interior extendable leg, such that the extended position is locked in place with a screw.
One of the problems with these techniques is the tendency of screws or other fasteners to work loose after fixation. Slight or extreme shock or vibration of the vertebrae, due to normal or rigorous activities of the patient, increases the risk that the screws may become loose or back out. If a screw becomes loose or unattached, the consequences can be significant for the health of a patient.
There remains a need for a locking device to not only lock a screw into a desired position, but also to prevent the screw from backing out. Further, there remains a need to achieve these goals without the need for auxiliary screws or separate components that may get lost in the patient's body. Thus, there is a need for an improved and simpler locking device that can be machined onto a component that will allow a screw to be locked into position and prevent the screw from backing out.